There have been many terrible events in the history of Northern Ireland's conflict, but few have seared the collective consciousness of its people as those on Friday, 21 July 1972, a day that became known as Bloody Friday.

By the end of the day, the IRA's Belfast brigade had detonated at least 20 bombs across the city.

In just 75 minutes of violence, nine people were dead and some 130 more were mutilated, injured and mentally scarred by what they had witnessed.

You could hear people screaming, crying and moaning. The first thing that caught my eye was a torso of a human being in the middle of the street

Police officer at the scene

From the outset, the IRA's bombing of the city caused widespread chaos and stretched the security forces to the limit.

Such was the scale of the attack, witnesses at the time remember seeing people running in all directions, not knowing where the bombs were being detonated.

As one report at the time described the scene, "it was impossible for anyone to feel perfectly safe".

Car bombs

While the scale of the attack was huge, it was two car bombs that between them claimed the nine lives - one at the Oxford Street bus station in the city centre, the other outside shops in Cavehill Road in north Belfast.

Victims: Many were blown to pieces

At Oxford St, the busiest bus station in Northern Ireland, four Ulsterbus workers and two soldiers were killed.

When the emergency services reached the scene, they found that some of the victims had been literally blown to pieces, leading to initial estimates of a death toll of 11.

At the Cavehill Road bomb, the victims were two women and a 14-year-old schoolboy.

Of the 130 injured, 77 were women or children out shopping in the city centre.
One police officer at the scene recalled the events for the BBC series Provos in 1997.

"You could hear people screaming, crying and moaning. The first thing that caught my eye was a torso of a human being lying in the middle of the street," he told the series.

Collapsed ceasefire

In terms of furthering its cause among nationalists, the IRA's decision to carry out the Bloody Friday attacks proved to be a disaster.

Earlier in the year, the IRA had experienced a massive propaganda and recruitment boost after the Parachute Regiment killed 13 protesters during Bloody Sunday in Derry. Many joined believing that they had no other way to defend their communities.

It required only one man with a loud hailer to clear each target area in no time.

Former IRA leader Sean MacStiofain

By June, the organisation felt confident enough to call a ceasefire and hold secret talks with British ministers in London. Those talks came to nothing and the ceasefire collapsed.

Bloody Friday was part of a deliberate decision to ratchet up a campaign and make normal life impossible.

But after causing the deaths, the IRA tried to blame the security forces for failing to act on warnings.

Ultimately Bloody Friday revealed a side to the organisation that many who had joined in the wake of Bloody Sunday had not wished to acknowledge.

Within 10 days of the attacks, the army moved in to the Bogside area of Derry to take control of a part of the city that had become out-of-bounds, marking the beginning of a long war of attrition by both sides.

Denials

In later years, an IRA leader at the time, Sean MacStiofain, said that the aim of the Bloody Friday attacks had been to cause financial damage - but he still refused to accept responsibility.

"It required only one man with a loud hailer to clear each target area in no time," he said.

"Republicans were convinced that the British had deliberately disregarded these two warnings for strategic policy reasons."

Bloody Friday was by no means the last atrocity of 1972. It remains the bloodiest year of the conflict in Northern Ireland.